Residents said the heavy smoke darkened their hallways and made breathing extremely difficult.

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A three-alarm fire in New York City Saturday morning left 37 people injured, including one child and four adults who were in critical condition, fire department officials said.

The fire broke out in an apartment on the fifth floor of a building in Melrose section of the Bronx at around 7:45 a.m. ET. Authorities said smoke from the fire quickly spread throughout the 27-story high-rise.

"When we opened the door to put the fire out, it just fills the building up -- the hallways, the stairs -- up with smoke," said FDNY Deputy Assistant Chief Jack Mooney.

Residents said the heavy smoke darkened their hallways and made breathing extremely difficult. At least 12 people had to be carried down by firefighters, authorities said.

"Smoke was so thick on 22 and the fire started on five," said building resident, Dolores Carter, an asthma sufferer who had to be helped down by firefighters and needed to use a ventilator afterwards. "It was a trying time."

Officials said most of the injuries were minor, but four adults and a child were being treated for smoke inhalation in hyperbaric chambers at Jacobi Medical Center.

Red Cross workers were on the scene assisting evacuated residents.

There is no word yet on what caused the fire.

The fire broke out on the fifth floor of a building in the Melrose section of the Bronx at around 7:45 a.m.

Residents said heavy smoke filled up hallways causing widespread panic throughout the 27-story building. At least 12 people had to be carried down by firefighters, authorities said.

"Smoke was so thick on 22 and the fire started on five," said building resident, Dolores Carter, who had to be helped down by firefighters and needed to use a ventilator. "The smoke was coming out of my window."